Sydney's finest house and arguably its best apartment have hit the market at the same time.

And, buoyed by a string of strong sales last year, more vendors are set to list their trophy homes in coming weeks.

Wednesday's international launch through Christie's International of the Fairfax family's Point Piper waterfront property, Elaine - which industry experts say could be worth $100 million - coincides with the listing of an entire-floor apartment in Bennelong next to the Opera House for $30 million.

A entire-floor apartment in Bennelong is up for grabs

''It's also indicative of the market confidence both here and internationally.'' A non-waterfront estate is also set to come up for sale next week with a price tag of more than $60 million.

Mr Malouf and Michael Pallier of Sotheby's International are selling the palatial, 700-square-metre apartment overlooking Sydney Harbour for Margaret Maloney, the widow of pub baron Cyril Maloney who died last year aged 93.

''There's none other like it,'' Mrs Maloney said last week on a tour of the Macquarie Street apartment.

Mrs Maloney has lived in the building, once nicknamed the Toaster, since she and her late husband bought all four apartments on level 11 in 1999 for $13.9 million.

They had them gutted and redesigned as one apartment by architect Michael Suttor, with interiors by Michael Love.

The amalgamated spread features a vast open-plan living, dining and kitchen area with harbour views, and the four bedrooms (including a palatial master suite with his and hers dressing rooms and en suites and a study) on the east side overlooking the Botanic Gardens.

As well as five car spaces, six bathrooms and a second kitchen, it also has a second living area, formal dining room, cellar and a billiards room with a wet bar.

''If I was to make an educated guess as to the buyer, it wouldn't surprise me if this went to a Hong Kong businessman or family,'' Mr Malouf said.

It has been a long drum-roll for Wednesday's launch of the Fairfax family's Point Piper beachfront estate Elaine since news broke of its sale last September.

It is listed with Ken Jacobs, of Christie's.

The 6986-square-metre estate with the three-storey Victorian mansion, tennis court and gardens down to Seven Shillings beach, is considered the largest privately held estate on the harbour.

Elaine was built during the 1860s and has been in the Fairfax family since 1891 when it was purchased by Geoffrey Fairfax for £2100.